You may have heard the claim that Roman Emperor Constantine I “invented” the Catholic Church sometime in the early part of the 4th Century. But this is simply not true.
The church was called the “Catholic Church” within the first 75 years of its existence. We see this in the writings of Ignatius of Antioch, a disciple of St. John the Apostle. He calls the church “catholic” to distinguish it from the heretics of his day: “Wherever the bishop shall appear, there let the multitude [of the people] also be; even as, wherever Jesus Christ is, there is the Catholic Church” (Epistle to the Smyrnaeans 8, written in A.D. 107).
Ignatius also describes the church in very “Catholic” ways, such as its belief in the real presence of Christ in the Eucharist: “…the Eucharist is the self-same body of our Savior Jesus Christ which suffered for our sins, and which the Father in His goodness afterwards raised up again” (Epistle to the Smyrnaeans, 7). He also writes of the Episcopal leadership of bishops, priests and deacons: “…nobody’s conscience can be clean if he is acting without the authority of his bishop, clergy and deacons” (Epistle to the Trallians, 7).
Irenaeus of Lyons, writing around A.D. 190, notes that the Bishop of Rome has authority over the other bishops throughout the world: “…it is a matter of necessity that every Church should agree with this Church, on account of its preeminent authority” (Against Heresies, 3, 3, 2).
Another important point about the early church: It is a fact of history that Christians were under the pastoral care of the Church’s leaders and did not look to the Bible alone as their authority. Even if they wanted to, they couldn’t, because the Bible was not yet formed. For the first 15 or 20 years of the church’s existence, none of the New Testament books had been written. And it was not until centuries later that the bishops of the church determined, under the Holy Spirit’s guidance, which books belonged in the Bible. The Council of Hippo (A.D. 393) created the list of the Old and New Testament books, which is the same as the Roman Catholic list today. The Council of Carthage in A.D. 397 formulated the same list of canonical books, and it is this council that many Protestant Christians take as the authority for the New Testament canon of books. Interestingly, the Old Testament canon from that same council is identical to Roman Catholic canon today (46 Old Testament books; in the 16th Century, Protestants removed 7 Old Testament books).
So it is clear that well before the time of Constantine, the church was certainly Catholic – in name, in hierarchy and in practice. Constantine gave the Catholic Church status as an officially recognized religion within the Empire; he did not create it.